Furnace bridge wall cooling and air feeding construction



1952 J. T. BAILEY 2,606,513

FURNACE BRIDGE WALL COOLING AND AIR FEEDING CONSTRUCTION Filed May 12, 1944 & INVENTOR J.T.BA\LEY 4 v I m Patented Aug. 12, 1952 FURNACE BRIDGE WALL COOLING AND AIR FEEDING CONSTRUCTION Joyce '1. Bailey, Oklahoma City, Okla., assignor to Phillips Petroleum;Company, a corporation of Delaware Application May 12, 1944, Serial No. 535,370

4 Claims. (01. 110-68) This invention relates to furnaces and other heating equipment and methods of operating the same in which a portion, such as a fire wall, is subject to such heat that its strength or life of service is impaired by operating temperatures to:

which it is subjected. This invention has particular relation to protecting the bridge wall of a cracking furnace by two streams of air, one stream being the air used in combustion in a furnace and the other stream being drawn in for:

cooling purposes by the draft of the stack.

One object of this invention is to cool the .enclosed structure which supports the bridge wall or other furnace structure, with air, under surrounding atmospheric conditions, by directing its s flow, said flow being induced by the difference in pressure of the atmospheric pressure and the reduced pressure in the stack and other portions of the furnace caused by stack draft, the air being supplied to thevarious parts of the supporting:

structure and being drawn off with the combustion gases through the stack.

Another object of the invention is to supply portions operating under the more severe conditions of temperature with additional cooling air while cooling other parts with the normal complement of combustion air.

Another object is to proportion the amount of cooling air supplied to a furnace element to the relative temperature. thereof.

Another object is to prevent the formation of stagnant air pockets by. controlling the air flow throughout.

Another object is to provide a separate cooling system for the hottest portion of the structure which system may be varied or changed as to volume of air being used without interfering with the operation of the heating means, such as burners.

A further object is to provide a furnace in which the cooling air does not lower the furnace temperature appreciably because the major portion of the cooling air passes more or less directly to the stack, so that the heat lost from the fire box is only the amount removed from the bridge wall and other cooled structure, and in which no additional combustion air is admitted to improve the cooling because such additional air would require additional fuel in order to maintain the required fire box. temperature, and/or proper combustion.

Other objects are to provide improved details" of furnace construction, economy of materials employed and proper arrangement of parts to provide streamlined flow of air.

Numerous other objects and advantages will be apparent to those skilled in the art upon reading the accompanying specification and claims and studying the accompanying drawings.

In the drawings:

Figure l is an elevational view taken in cross section of a furnace having a bridge wall embodying the invention. V a

Figure 2 is an enlarged. cross sectional view of the bridge wall of Figure 1 showing details of construction.

Figure 3 is a flow connection diagram drawn in perspective and showing only the flow connections and orientation of the ducts of Figures 1 and 2; with the form of the ducts simplified and the top of duct 2| flattened for ease of illustration and with all other parts removed for purposes of clarity, all as employed in the invention.

In Figure 1 a cracking furnace generally designated as 4 is shown as an illustrative embodiment of the invention. While the invention-is shown applied to abridge wall of a cracking furnace it is obvious that the invention may be employed wherever an element needs to be cooled in a situation of like nature.

Furnace 4 consists of a combustion air chamber 5, a radiant heat section 6, a bridge wall I, a convection heating section 8 and a stack 9.

Section 6 and 8 may be provided with a suitable cracked in the case of a cracking furnace. While pipes II are shown, obviously other forms of operating structure such as tanks may be employed depending on the use of the furnace without effecting the practice of the invention, the invention requiring only a burner or other source of combustion l2, a stack or other exit for combustion gases 9 and a bridge wall or other structure to be cooled I.

In Figure 2 suitable structure for the bridge wall or other structure to be cooled is shown. The bridge wall referred to generally as 1 consists of a supporting structure of two or more I beams I3. I beams I3 have openings l4, l5 and I6 cut through their webs. This cutting may be by an oxoacetylene torch. Above the point I! the flanges of the I beam are cut away leaving an upstanding web portion [8.

Resting on the top of flanges l1 and the tops of webs i8 is a transverse I beam l9. Passing 'desc'ribedwilldrive all {gases up stack 9.

essential that these air ducts be leak-proof as a small amount of leakage from one duct to another is unimportant as long as there is not so much leakage as to make the substantial control of combustion air in 25 impractical.

Secured to the supporting structure l3 and I9 is the brick. work'22 which may befin sectional blocks as shown or may be cast as'a monolithic structure. The construction of refractory walls is well understood in the art and the refractory material 22 may be secured to the supporting.

structure in any well known manner.

In Figure 3 the orientation of the ducts for the air are shown. For simplicity .duct 2| is "shown square although actually it could be are shaped (See Figures 1 and 2). Figure 3 is schematic. Air for combustion enters at H and I 'on each side of the furnace, the amount of air entering being controlled by a damper 23 in each of pipes l4 and I5 and a handle '24 is provided for setting the position of each of the dampers. The air in M and i5 passes down into conduit 25 to comb-ustion air chamber 5 where it passes into furance 4 through burnerv |'2. Burner I2 is supplied with suitable fuel such as oil, coal or gas, gas being shown for purposes of illustration. The gas comesin through lines 2!; controlled by valves 21. However, a coal grate or other heating means could be employed in place of .burners l2.

Additional cooling air enters through ducts l6 and 2| and passes down central passage 28 to emerge from exit 29. While exit 29- is shown near the base of the bridge wall I it is obvious thatif desired duct .28 could be extended into close proximity to the base of stack 9, or duct 28 can extend. part way up the stack if desired. PartSl is thus cooled the desired amount without change of combustion or temperature in the furnace. As-shownin-Figm'e 2 exit '29 is connected to duct l6 by duct 28 and to duct M by duct 28 and duct 39, a hole being cut in the .Webof I beam 1 9. to allow communication between duct 2| and. duct as leading to duct 2.8. The position of the end of exit 29 is shown'at a point where lower than atmospheric pressure existsin the furnace because of the draftinduced bysstack 9. However 'if force air feed is fusediin ducts 2|, Hi, I5 and 1M it is immaterial "where exit '29 .is placed, provided air from-29 .is'no't added to the combustioneir travelingthrough 25, 'asthe forced draft Duct 34 connects 'the'righthand ducts :I4 and I5 with duct :2 5 and duct .33 ;conne-cts.'t'he left hand ducts M and IS with duct;2.5.

Ducts I6 and I8 are controlled by dampers 23 in a similar manner toducts M and 15. The temperature of 3| may be measured by a pyrometer (not s'hown) or judged byeye through peep hole 32 and automatic damper control of ducts l6 and 2| actuated by the pyrometer may be devised to keep 3| atasuitable'temperature.

Operation:

In the prior art'them'ethod of cooling enclosed supporting members :and the interior of bridge 1 waHs andlother such structure has been by directing only .the incoming airifor combustion .to the various :parts,-orl by such direction of air as to disturb the combustion. mixture, the amount of fuel consumed and/or the temperature in the useful portion of the furnace.

In the .present invention as shown in the drawings the combustioniaircoming from the atmosphere maybe regulated by sdampers 23 in ducts 1-4 and i5 sothat exactly the right'amount of air 'will be thrownintoftheifurnace through burners l2 by draft from stack 9 and suction induced by injection of fuel through pipe 26. If desired a blower (not shown) may be provided in duct 25 for the purpose of forcing the draft, but whether 5 such blower is provided or not in the operation of my invention the amount of combustion air supplied vis made substantially constant and of substantially the same proportion to the fuel as is most eflicient in the operation of the furnace 110 for the purposes desired.

portion of the bridge wall in which the temperature is lessextreme and more constant.

The upper portion 3| of the bridge wall is generally the hottest and for cooling this upper portion air from the atmosphere is allowed to enter 2o ducts l6 and 2| by proper adjustment of dampers 23. This air passes through duct 28 and out exit 29 to be drawn up stack 9 by the draft caused by expanding Warm air in the stack. The cooling air passing through ducts l6 and 2| direct to the stack 9 does not lower the furnace temperature .any substantial amount as the stack has suilicient capacity for the additional load. The amount of air flowing through ducts l6 and 2| can be varied from time to time according to 30 the temperature or appearance of the top of bridge wall 1 as observed through a peep hole such as 32. Extreme changes in the amount of air admitted through ducts I6 and 2| will have noefiect on the combustion of gases in burners I2 and in conditions generally throughout the entire furnace. It is advantageous to cool the hot part with :any desired amount of air and use the combustion air .for cooling the less heated portion. There are no stagnant areas in ducts l4, .l5 l6 and 2| and the air flows smoothly through all the ducts without stopping at any place in the system.

The air coming out exit 29 is preferably cooler, orsubstantially thesame temperature as the sur- .rounding gases, and flows over to the stack. If

exit 29 is placed inside the stack then the temperature of air in 29 is immaterial.

By having duct l9 below and duct 2| above it, .I beam I9 is protected from warping caused by overheating and by having ducts l4. l5 and I6 .throughits upper portion .1 beam 13 is likewise protected .from warping heat.

Obviously, changes in design and arrangement of parts may be made without departing from the -scopeof the invention which scope is defined in the following. claims.

.Havingdesciibed my invention, I claim:

1. .A furnace comprising a refractory housing forming a chamber, a hollow bridge wall exitending transversely of the chamber entirely across the space" between the side walls thereof, the side walls of the housing having a series of openings aligned with the space of the hollow bridge walL the Ibridge wall having a crown extending into the chamber to divide it into affirst heating section and'a second heating section each in communication with the other, a combustion "heater connected to the first heating section, a stack for said second heating section,

7 a pair of separate duct systems lying within'said hollow bridge wall, the inlet ends of said duct systems communicating with .the openings in the side walls of said housing, one .of said duct systems discharging intosaid second heating section, and a duct connecting the other duct system with said combustion heater whereby the air flowing through said first duct system cools a portion of said bridge wall before introduction into said second heating section and the air flowing in said other duct system coolsanother portion of said bridge wall and is preheated before it is delivered as primary combustion air to said combustion heater.

2. In the combination of claim 1', separate means in each of said duct systems for varying the amount of air flowing through each system respectively.

3. In the combination of claim 1, apair of parallel vertically disposed I-beams lying within said bridge wall and a horizontally extending I- beam resting on the upper ends of said pair of I-beams, said I-beams forming part of the structure of said bridge wall.

4. In the combination of claim 1, a pair of parallel vertically disposed I-beams lying with- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 288,418 Ford Nov. 13, 1883 747,648 Scanlan Dec. 22, 1903 1,833,677 Hawke Nov. 24, 1931 

